1. Field of the Invention
This invention relates generally to communications. More particularly, it relates to throttling on ingress to and egress from a central system for voice or text-based communications.
2. Background of the Related Art
9-1-1 is a phone number widely recognized in North America as an emergency phone number that is used to contact emergency dispatch personnel. Enhanced 9-1-1 (E9-1-1) is defined by an emergency call being selectively routed to an appropriate PSAP, based on a special identifier (a TN or “telephone number” that is either an ANI or “Automatic Number Identification” that identifies the caller's phone or the TN is a P-ANI, or “Pseudo Automatic Number Identifier”, also referred to as “ESxK”, that only identifies the PSAP the call should route to and the company routing the call), and includes the transmission of callback number and location information when 9-1-1 is used. E9-1-1 may be implemented for landline, cellular or VoIP networks. A Public Safety Answering Point (PSAP) is a dispatch office that receives 9-1-1 calls from the public. A PSAP may be a local, fire or police department, an ambulance service or a regional office covering all services. As used herein, the term “PSAP” refers to either a public safety answering point (PSAP), or to an Emergency Call Center (ECC), a VoIP term.
Regardless of the network type, a 9-1-1 service becomes E-9-1-1 when automatic number identification and automatic location information related to the call is provided to the 9-1-1 operator at the PSAP.
The current 911 infrastructure is designed to route a live voice call to a local public safety answering point (PSAP). This requires that voice circuits be available. The result of an E911 call is a direct circuit switched voice connection between an emergency service requestor and a suitable responder. 911 is further enhanced with the ability to deliver location over a data channel in parallel to the call. The location data is typically staged in a database that is queried by the PSAP to determine location information.
FIG. 6 shows a conventional landline public safety access point (PSAP) to automatic location identifier (ALI) connection.
In particular, FIG. 7 shows a PSAP 400 connected to one Automatic Location Identifier (ALI) database 401. Upon receiving a 9-1-1 call, the PSAP 400 queries the ALI 401 for location data. The ALI database 401 accepts the query from the PSAP 400 for location. The query includes the telephone number of an emergency caller. The ALI database 401 relates the received telephone number to a physical street address and provides that street address (location information) back to the PSAP 400 in a manner that works for the customer premise equipment (CPE) display at the PSAP 400.
An ALI is typically owned by a local exchange carrier (LEC) or a PSAP, and may be regional (i.e. connected to many PSAPs) or standalone (i.e. connected to only one PSAP).
FIG. 7 shows a context diagram for a conventional non-landline positioning center (e.g., an Internet based Voice over Internet Protocol (VoIP) positioning center).
In particular, the ALI database 401 includes a conventional emergency services key (ESQK or ESRK) in a location request sent to an appropriate positioning center 402 (XPC). The emergency services key (ESQK or ESRK) is used by the positioning center 402 as a key to look up the location and other call information associated with the emergency call.
In non-landline telephony, the PSAPs 400 query the ALI 401 for location information. However, the ALI 401 is not pre-provisioned with location data for non-landline calls (e.g. cellular, VoIP etc) and must communicate with other network entities to obtain and deliver location data to the PSAP 400.
911 calls require voice circuits to be available to complete the voice call to a PSAP. For the most part, PSAPs are capable of receiving only voice calls. Connectivity with a PSAP, established either through the existing time division multiplexed (TDM)-based emergency services network (ESN), or directly over the public switched telephone network (PSTN) to the PSAP, is managed through dedicated telephone switches that cannot be directly dialed.
The present inventors have appreciated that during times of regional crises, such as during a hurricane, the local wireless infrastructure can become overloaded by call volume. This was experienced during the Sep. 11, 2001, terrorist attacks during which voice telecommunications along the east coast was subjected to service failures.
Existing technology uses a limit on the number of voice circuits or network bandwidth available for voice calls or other calls based on other technologies. Existing technology is not dynamic and cannot be controlled from a central access point to a system. Moreover, existing technology cannot deliver location information at the time of call set up and cannot take advantage of the diversity, redundancy, and resiliency of IP networks.